1. Field of the Invention
This invention relates to a roof panel mounting clip for securing roof panels of sheet metal to a supporting structure. More particularly, the invention relates to a roof panel mounting clip permitting the roof panels to move relative to the supporting structure, e.g. upon thermal expansion or contraction of the panels.
2. Prior Art
A prior art roof panel mounting clip designed to permit the roof panels to move relative to the supporting structure without subjecting the clips or the supporting structure to undue stresses is shown in Swedish Pat. No. 222,382. This mounting clip comprises an anchoring member having a horizontal base flange and a vertical web with a horizontal closed slot, and a tab member slidably mounted on a bridge portion defined in the vertical anchoring member web between the slot and the upper edge of the web. The anchoring member is adapted to be secured to the supporting structure by nails or other suitable fasteners, whereas an upstanding portion of the tab member is adapted to be engaged with a longitudinal flange of one of two contiguous roof panels which are subsequently joined by seaming interengaged longitudinal flanges together to form a so-called standing seam in which the tab member is interleaved.
In this prior art clip the tab member is formed of a sheet metal strip inserted in the slot of the anchoring member web and folded upwardly upon itself about the bridge portion. The upwardly extending limbs are of approximately the same length and are offset in the longitudinal direction of the bridge portion such that they do not overlap one another in the seam, thereby minimizing the amount by which the thickness of the seam is increased in the region of the clip owing to the interleaving of the tab member. However, the cost of this advantage is a considerable waste of material resulting from the special shape of the tab member strip which is due to the offsetting of the limbs.
A further prior art clip is shown in Swedish Pat. No. 7802814-9 (Publication No. 420,008). In this clip, the tab member is also formed by a sheet metal strip folded upwardly upon itself about the bridge portion. However, the limb on one side of the bridge portion extends only slightly above the upper edge of the bridge portion. In order that the tab member may be capable of withstanding the forces applied by the roof panels tending to rip it away from the bridge portion, the limbs are welded or riveted together immediately above the upper edge of the bridge portion. However, the welding or riveting of the limbs complicates the production of the clip.